Embodiments of the present specification generally relate to a power distribution system and more specifically to regulation of voltage in medium and low voltage power distribution systems.
In recent times, increased use of commercial photovoltaics (PV), residential photovoltaics, and electric vehicles (EV) by customers has resulted in fluctuations in a voltage profile along a feeder of power distribution systems. Accordingly, voltage regulation devices are being employed in conjunction with the feeder of the power distribution systems for circumventing the fluctuations in the voltage profile along the feeder. Typically, these voltage regulation devices are either based on mechanical and/or electronic on-load tap changers (OLTCs) or based on power electronic converters/inverters.
Conventionally, mechanical OLTCs have been used in high and medium voltage power distribution systems. However, while mechanical OLTCs are relatively inexpensive, the mechanical OLTCs are less suitable in low voltage power distribution systems. Also, large voltage fluctuations in the power distribution systems cause excessive operation of the mechanical OLTCs, which in turn results in increased wear and tear of the mechanical OLTCs.
Recently, fully electronic or electronically assisted (hybrid) OLTCs have been employed in the power distribution systems. These OLTCs are capable of operating at a higher switching frequency. Furthermore, these OLTCs have a longer life cycle due to absence of arcing during tap changing. However, the fully electronic or the electronically assisted OLTC solutions are more complex. Also, although the voltage regulation devices employing power electronic converters/inverters offer very high flexibility and enhanced functionalities, these voltage regulation devices are exceedingly high in cost.
Moreover, the installation cost of the existing voltage regulation devices is significantly higher when compared to the cost of individual voltage regulation devices. Also, when new PV installations and electric vehicles are connected to the feeder of the power distribution system, the feeder experiences voltage violations in a range from about ±1% to about ±2% from higher or lower limits of voltage for the feeder. Use of a higher number of new PV installations or EV connections results in the feeder experiencing a higher percentage of voltage violations. Currently, network operators address the issue of voltage violations via use of greater voltage regulation capabilities in order to avoid high installation costs in the future. Consequently, the currently available voltage regulation devices for low voltage power distribution systems are configured to provide voltage regulation in a range from about ±6% to about ±10% of the nominal voltage. However, in most cases this high value of voltage regulation may not be required.